Abstract: A phase locked loop (10) comprising: a tuneable oscillator (12); a mixer-based phase sensitive detector (18) to receive input signals from the tuneable oscillator (12) and a reference signal (20); a cycle slip detector (26) to receive input signals from the tuneable oscillator (12) and the reference signal (20), the cycle slip detector (26) being configured to generate an output signal when two consecutive pulses are present in one of its input signals without an intervening pulse in the other of its input signals; coarse tune signal means (32, 34) to receive the output signal generated by the cycle slip detector; and adding means (24) for adding a signal output by the coarse signal means (32, 34) to a signal output by the phase sensitive detector (18) to control the frequency of the tuneable oscillator (12).

Abstract: A phase locked loop (10) comprising: a tuneable oscillator (12); a mixer-based phase sensitive detector (18) to receive input signals from the tuneable oscillator (12) and a reference signal (20); a cycle slip detector (26) to receive input signals from the tuneable oscillator (12) and the reference signal (20), the cycle slip detector (26) being configured to generate an output signal when two consecutive pulses are present in one of its input signals without an intervening pulse in the other of its input signals; coarse tune signal means (32, 34) to receive the output signal generated by the cycle slip detector; and adding means (24) for adding a signal output by the coarse signal means (32, 34) to a signal output by the phase sensitive detector (18) to control the frequency of the tuneable oscillator (12).

Abstract: Embodiments of the present invention relate to an improved man-machine interface for an apparatus. The interface comprises at least one graphical representation of a controllable parameter.

Abstract: A waveform generator for generating a smooth version of an original waveform which contains abrupt transitions, includes a phase accumulator incremented at successive sampling times to produce an output representative of the phase of the original waveform, a phase scaler arranged to convert the residual contents of the accumulator following a transition from phase to time, computing means responsive to the time to calculate a number of samples along a smooth transition, each offset by that time from the sampling times, and a sequencer to replace the otherwise abrupt transition with the sequence of samples from the computed smooth transition.

Abstract: Various tester configurations are provided that injects test signals into nets (e.g. 24). Non-linear characteristics of the response are detected (e.g. harmonics, do offset) and used to assess the adequacy or otherwise of device connections in the net.

Abstract: A waveform generator for generating a smooth version of an original waveform which contains abrupt transitions, includes a phase accumulator incremented at successive sampling times to produce an output representative of the phase of the original waveform, a phase scaler arranged to convert the residual contents of the accumulator following a transition from phase to time, computing means responsive to the time to calculate a number of samples along a smooth transition, each offset by that time from the sampling times, and a sequencer to replace the otherwise abrupt transition with the sequence of samples from the computed smooth transition.

Abstract: A low noise sinusoidal signal at a desired output frequency is synchronised using a first variable frequency oscillator (1) and providing a feedback control loop around the first oscillator (1) to generate a feedback control signal in successive frequ comparison steps using second and third frequency reference signals (44, 42). Each of the second and third frequency reference signals are derived from a first frequency reference signal, the second frequency reference signal (44) being compared with the output frequency of the first oscillator (1) to generate a frequency difference signal (43), and said frequency difference signal ( being compared in frequency with the third frequency reference signal (42) to generate said feedback control signal for the first oscillator (1), the frequency of the third frequency reference signal (42) being equal to the difference of the frequency of the se frequency reference signal (44) and the desired output frequency.